Surge Tubes?

Vince Luciani · Post by **Vince Luciani** » Jan 29th, '07, 17:00

I see alot of discussion recommending that "surge tubes" be a component of a well designed exhaust system. What are they and where can I purchase them? I am repowering with Cummins 315 hp Remans and want to do it right.

As always, thanks in advance for the info.

Vince Luciani

bob lico · Post by **bob lico** » Jan 29th, '07, 17:42

take the port engine and go over the top with 4" ss pipe then canter the down 90 degree ss wet exhaust at the bottom you use a 70 degree 6"ss fitting on to you exhaust this will put you on the outside stringer so the space between stringers will be empty for a fish box or whatever.the starboard comes out of the turbo and goes up to within 2" of the engine hatch(allowing for heat wrap)forming a gentle rolling 180 degree turn then a 70degree a the bottom this wll also fall out between the outside hull and stringer.you end up with two giant fish boxes in the cockpit deck and no need for a surge tube if you use mufflers.i used blue silicon hose after the wet exhaust and from the 70 degree fitting to the muffler there after 6" wet exhaust hose. very quiet compare to fiberglass pipe.i have done extensive testing with 5 sets of props and engine shifted back 4" as well as any other weight i come put in cockpit.boat runs 40 and cruise at 31knots.i will change props and settle down to a 28 cruise.can not dock it!!!!

Bruce · Post by **Bruce** » Jan 29th, '07, 18:43

Surge tubes are an extension of the exhaust that allow a "surge" of water to accumulate instead of going up the exhaust and drowning out the engine.

Instances would be hard backing and the up and down motion of the boat in the water.

Do all boats need them? No. It depends on the exhaust design and owner preference.

I make my own and finish depends on owner specs.

Most companies that make risers do or can recommend a company for tubes.

The two pics below show different examples. The top is 4" from the Volvo repower, no gel coat finish.

The bottom is from a Cummins QSB330 with riser, surge tube and gel coat finish with stainless inserts. 6" diameter.

Both owners had past problems in other boats with drowning engines and both wanted tubes with mufflers.

Bob, I can't see for the life of me where you can detect any sound difference between fiberglass tube and hose with the decks down and the engines running.
Better hearing than mine.

Terry Frank · Post by **Terry Frank** » Jan 29th, '07, 19:23

Thanks Bruce. I knew what a burp tube was in walkin freezers but wasn't sure what a surge tube was.

Br,

Terry

Russ · Post by **Russ** » Jan 29th, '07, 19:36

What muffler fits outboard of the stringer? My exhaust currently runs down the center over the shaft.I want to move it outboard but also wanted a muffler. Exhaust is 5". I know the mufflers I have now will not fit, will hit deck. Maybe just a surge tube?

thuddddddd · Post by **thuddddddd** » Jan 29th, '07, 19:37

Bruce the black wrap(some kinda insulation ) on riser on the cummins install, factory or did you do it? what is it, and can it be bought

CMP · Post by **CMP** » Jan 29th, '07, 19:51

You're so far from needing any kind of black wrap stuff that it's not even funny. Get the convicts back to work so we can start rebuilding...

CMP

thuddddddd · Post by **thuddddddd** » Jan 29th, '07, 19:59

ahhhhhhhh, but diesel dave isn't. All the new lines got dropped off today. More stuff off the motors to go to holtz for boiling(unless you got a better source) just finished cleaning up from getting more flake off the dump truck motors. Dave claims he's got a source for new turbo blankets and exhaust wraps for really short $$$ of course it's from some 3rd world country that isn't too worried about osha regs

Bruce · Post by **Bruce** » Jan 29th, '07, 20:07

Its fiberglass exhaust hard coat.
The people who build my risers put it on.

Terry Frank · Post by **Terry Frank** » Jan 29th, '07, 20:40

Great. Happy for all the info. What the f*** is a surge tube. Sorry for being stupid..

Terry

bob lico · Post by **bob lico** » Jan 29th, '07, 20:59

bruce i had the deck off when i tested the boat,mainly to check for leaks.the trident exhaust seamed to muffle the noise somewhat these are full lenth (10') from muffler to stern.
the muffler is a centek mini max 6".the deck is a glass teck with a noch remove at the web that goes over the muffler.i glassed in two reinforcment forward and aft of the muffler.than made a 2"partition aft of the forward compartment and from that point all the way to the stern is a 51/2 foot fish compartment with pull out insulated box as far as the speed this is ideal diesel conditions.fuel is 40degrees and 40degree cold air forced in the turbo thru a alluminum ram air scoop (lika a pro stock.)the scale on the travel lift showed under 10,000 lbs and the bottom is all tricked out like tom holz`s did on his 31.incidently the 31 fbc will rise to the two bottom strakes at 37knots.for safety sakes you better drive with your knees on the flybrige deck and the seat at your back braced in.i had a 31 jupiter as a chase boat 10' to my port checking perfect plane.you absolutly have to have the captains rudders to maintain a straight course.

Vince Luciani · Post by **Vince Luciani** » Jan 30th, '07, 21:35

As always, thanks for the info. The surge tubes make alot of sense to me and I will be installing in my setup.

Vince

Capt. DQ · Post by **Capt. DQ** » Jan 30th, '07, 23:58

Russ,

5" large centex muffler exhaust will fit outside of the outside stringer, my did.

Bruce, looking clean on the Time Machine install. What type of sea strainer did you use on the genset.

R,
DQ

Bruce · Post by **Bruce** » Jan 31st, '07, 06:49

Groco ARG 3/4 npt.

Brianb · Post by **Brianb** » Jan 31st, '07, 23:20

Interesting discussion on the surge tubes. I had orginally thought I needed them, but in the last 8 years, we have not had an instance where water coming in the pipes was a problem for the motors (6bta) in my 31s. My guys spend a whole lot more time in hard reverse in Guatemala than I have seen anywhere else. We do use the exterior flaps, and have 5" straight pipes, no muffler. I am working on getting some of the newer shapes of mufflers to fit.

Brianb

scot · Post by **scot** » Feb 2nd, '07, 15:54

Bruce,
Do you like the fiberglass wrapped risers vs jacketed? Can you put you bare hand on one of them with the engine running?....without going to the emergency rooml.

John Jackson · Post by **John Jackson** » Feb 8th, '07, 23:03

Bruce, you do some nice work. Any reason you don't paint the bilge?

Bruce · Post by **Bruce** » Feb 9th, '07, 04:06

I very seldom get an owner who gives me unlimited resources when working on his boat.

I break down all the costs when a customer comes in for a repower estimate and they choose how they want to go.

In the first picture above the boat I just finished, I had pressure washed the whole hull area to remove 30 years of grease and oil.

I painted the engine compartment areas and center epoxy white. The owner didn't want to spend any money to do under the back deck as it came out very clean and with the decks down who's gonna know he said.

The second boat had all the hull areas painted fore and aft. It was still in the construction mode as shown by Capt Pats unfinished air box.

For the most part I don't have the luxury of some outfits that take two to three years to repower a boat. I do them in 2 to 4 months. Most of my owners want their boats back to be able to use them.

It seems I'm more the working mans boat repower center who gives the owner the option to chose as much or as little(to a point) work as they want done. Some go on to paint the bilge spaces after I'm done.

Bruce · Post by **Bruce** » Feb 9th, '07, 04:10

Scot,
I would much rather have the hard coat, fiberglass wrapped material.

Its not burning hot to the touch but does get very warm. The problem with blankets is its hard to seal the dry temp areas 100%. That leaves the potential for oil in a leak to ignite against a pipe that can get well over 500 degrees.

bertram31.com

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